This invention relates generally to gas turbine engine turbines and more particularly to methods for cooling turbine sections of such engines.
A gas turbine engine includes a turbomachinery core having a high pressure compressor, combustor, and high pressure or gas generator turbine in serial flow relationship. The core is operable in a known manner to generate a primary gas flow.
The gas generator turbine includes one or more rotors which extract energy from the primary gas flow. Each rotor comprises an annular array of blades or buckets carried by a rotating disk. The flowpath through the rotor is defined in part Typically two or more stages are used in serial flow relationship. These components operate in an extremely high temperature environment, and must be cooled by air flow to ensure adequate service life. Typically, the air used for cooling is extracted from one or more points in the compressor.
Conventional cooled turbine shrouds are supported by segmented hangers through which the shroud cooling air is supplied. This air is typically supplied through holes in the main body of the hanger. Once through the hanger, the air enters a plenum formed by the hanger and a sheet metal impingement baffle. The air then passed through the baffle and impinges on the shroud. In order to not damage the sheet metal baffle, it is preferable that the hanger holes be angled such that the air does not directly impinge on the baffle, or that the air is diffused before entering the plenum.
Current turbine shroud hangers either use straight holes which impinge directly on the baffle, or holes with partially cast diffusers. Turbine shroud hangers utilizing the direct impingement have experienced sheet metal baffle cracking due to excitation from the high velocity air coming from the hanger holes. Conventional cast diffusers require substantial space to be incorporated in and may require the use of quartz rods in the casting process.